Replies

1. 
   razzman | Feb 11, 2006 08:51pm | #1

   Greetings t,

   This post, in response to your question, will bump the thread through the 'recent discussion' listing again.

   Perhaps it will catch someones attention that can help you with advice.

   Cheers

   'Nemo me impune lacesset'
   No one will provoke me with impunity

2. 
   BillHartmann | Feb 11, 2006 10:12pm | #2

   A short or an open?

   A tone tracer (sounder) might find it for an open, but most of them can't feed a short. But in a different circumstance I have had some luck with with doin a "single ended" track connecting on lead to the wire and the other to a ground.

   But try it, what do you have to lose.

   If it is a short then ohming it and figuring out the resistance per foot would give you a clue as to where it its.

3. 
   DanH | Feb 11, 2006 10:54pm | #3

   If it's a short, and this is a single-wire heater cable, it should be possible to find the problem by applying an AC signal to the heater and then using a pickup coil to trace the wire. The traced signal will (more or less, depending on how "dead" the short) die at the point of the short.

   The old telephone pickup coils (now scarce as hen's teeth) were ideal for this kind of tracing, and you could often use plain old 60Hz AC (eg, from a "wall wart" transformer) as your AC signal, though another distinct frequency is better in terms of avoiding interference from regular wiring. Lacking the telephone pickup coil, the voice coil from an old loudspeaker would probably work, and a ham or other electronics hobbiest might provide you with the AC signal generator.

   If it's a two-wire cable then it's much trickier. Probably a time domain reflectometer (some cable TV and ethernet guys use these) would be able to tell how far down the wire the short is, but it wouldn't tell you where it was physically. You might be able to trace it using the the first technique above, but it would be much touchier.

   If ignorance is bliss why aren't more people

   happy?

4. 
   Rickie | Feb 13, 2006 04:56am | #4

   If I were a gambling man, which I am, I would bet that regardless of the excellent advise in the above and subsequent posts you will likely be taking up all the floor tiles. Is this in a bathroom, less than 50 square feet of floor tile? If so then I'd press my bet. Do you think this is a result of a nick in the wire caused by the notched trowel? Have you paid you tile sub yet? I'd prepare to R and R the tile and the heat pad, then instruct whoever is reinstalling the tile to be VERY careful. Perhaps bed the heat pad first and give it a thin protective layer of thin set before setting tile. Test it before final tile install. Mine is a pessimist's opinion, hope it is easier than that.

   
   

   ---

   Edited 2/12/2006 9:00 pm ET by Rickie

5. 
   SamT | Feb 13, 2006 04:56pm | #5

   Verify everything from the breaker up to the floor pad.

   If those check out, tear out the floor and redo.

   SamT

6. 
   bigman | Feb 13, 2006 09:46pm | #6

   1) A short in radiant floor heat is very rare as the wires are only close as they enter the wall to reach the Tsat, you are probably looking for an open circuit.

   2) On most radiant heat cable a tone tracer will not work if is is shielded (braided metal outercovering) and most of the heat cable I have installed is shielded.

   3) We have gotten lucky using a "pen" type non-contact voltage detector, lift 1 leg of the heat circuit so that the short is eliminated, turn the power on and slowly run the "pen" across the floor till it glows red

   4)This will indicated "power", slowly slide the pen across the floor in the direction of where you think the wire runs and look for the pen to go out, mark the spot with tape,  double check yourself by switching the power to the other wire, and trace the other side of the short.

   5) Good Luck